In conventional audio systems, a channel-based approach is employed. Each channel may for example represent the content of one speaker or one speaker array. Possible coding schemes for such systems include discrete multi-channel coding or parametric coding such as MPEG Surround.
More recently, a new approach has been developed. This approach is object-based, which may be advantageous when coding complex audio scenes, for example in cinema applications. In systems employing the object-based approach, a three-dimensional audio scene is represented by audio objects with their associated metadata (for instance, positional metadata). These audio objects move around in the three-dimensional audio scene during playback of the audio signal. The system may further include so called bed channels, which may be described as signals which are directly mapped to certain output channels of for example a conventional audio system as described above.
Dialog enhancement is a technique for enhancing or increasing the dialog level relative to other components, such as music, background sounds and sound effects. Object-based audio content may be well suited for dialog enhancement as the dialog can be represented by separate objects. However, in some situations, the audio scene may comprise a vast number of objects. In order to reduce the complexity and the amount of data required to represent the audio scene, the audio scene may be simplified by reducing the number of audio objects, i.e. by object clustering. This approach may introduce mixing between dialog and other objects in some of the object clusters.
By including dialog enhancement possibilities for such audio clusters in a decoder in an audio system, the computational complexity of the decoder may increase.
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